Monitoring of electrical energy by consumers and providers of electric power is a fundamental function within any electric power distribution system. Electrical energy may be monitored for purposes of usage, equipment performance and power quality. Electrical parameters that may be monitored include volts, amps, watts, vars, power factor, harmonics, kilowatt hours, kilovar hours and any other power related measurement parameters. Typically, measurement of the voltage and current at a location within the electric power distribution system may be used to determine the electrical parameters for electrical energy flowing through that location.
Devices that perform monitoring of electrical energy may be electromechanical devices, such as, for example, a residential billing meter or may be intelligent electronic devices (“IED”). Intelligent electronic devices typically include some form of a processor. In general, the processor is capable of using the measured voltage and current to derive the measurement parameters. The processor operates based on a software configuration. A typical consumer or supplier of electrical energy may have many intelligent electronic devices installed and operating throughout their operations. IED's may be positioned along the supplier's distribution path or within a customer's internal distribution system. IED's include revenue electric watt-hour meters, protection relays, programmable logic controllers, remote terminal units, fault recorders and other devices used to monitor and/or control electrical power distribution and consumption. IED's are widely available that make use of memory and microprocessors to provide increased versatility and additional functionality. Such functionality includes the ability to communicate with remote computing systems, either via a direct connection, e.g. modem or via a network. IED's also include legacy mechanical or electromechanical devices that have been retrofitted with appropriate hardware and/or software allowing integration with the power management system.
Typically an IED is associated with a particular load or set of loads that are drawing electrical power from the power distribution system. The IED may also be capable of receiving data from or controlling its associated load. Depending on the type of IED and the type of load it may be associated with, the IED implements a power management function that is able to respond to a power management command and/or generate power management data. Power management functions include measuring power consumption, controlling power distribution such as a relay function, monitoring power quality, measuring power parameters such as phasor components, voltage or current, controlling power generation facilities, computing revenue, controlling electrical power flow and load shedding, or combinations thereof. For functions which produce data or other results, the IED can push the data onto the network to another IED or back end server/database, automatically or event driven, or the IED can wait for a polling communication which requests that the data be transmitted to the requester.
The present disclosure is directed to a process of transferring data from an intelligent electronic device (IED) to external PC clients, via a network interface using the File Transfer Protocol (FTP).
File Transfer Protocol (FTP) is the standard application for transfer of files between computers attached to Transmission Control Protocol/Internet Protocol (TCP/IP) networks, including the Internet. FTP is a “client/server” application, such that a user runs a program on one computer system, the “client”, which communicates with a program running on another computer system, the “server”. The interface between the FTP client and server programs is officially defined by two Request For Comment (RFC) memoranda approved by the Internet Architecture Board of the Internet Society:
Postel, J. B., and Reynolds, J. K. “File Transfer Protocol (FTP)”, RFC959, October, 1985.
Braden, R. (editor). “Requirements for Internet Hosts—Application and Support”, RFC1123, October, 1989.
Normal operation of FTP requires the user to enter a user identifier and password for authentication on the server system. However, some system owners have the need to make some data files available as “public” data. To facilitate the transfer of such files, an informal protocol referred to in the art as “anonymous FTP” has been developed which allows a user to obtain data from an FTP server without requiring normal user identifier and password authentication. There is no formal specification of anonymous FTP, but the following informational RFC describes its use:
Deutsch, P., Emtage, A., and Marine, A. “How to Use Anonymous FTP”, RFC1635, May, 1994.
Traditionally, IEDs would transfer data using serial based download commands. These commands would be accessed via an RS232, and RS485 or an Ethernet port encapsulating the serial request with an Ethernet message using any Ethernet protocol such as HTTP or TCP/IP. For instance, host software or a “master” would make a request for a set of data from one or more memory registers. At that point, the IED slave would then communicate the data stored in the memory registers back to the host software utilizing a serial transfer. This technology is inherently limited because host software traditionally is limited by the amount of memory registers that it would be able to accept at any one time. For example, if the serial based protocol is Modbus, a recognized industry standard protocol, most software master systems are limited by the protocol definition to 256 bytes of data that can be transferred at any one time. Thus, to pull large amount of data, many such requests would have to be sent to the meter repeatedly. This would create many delays due to processing and data traffic.
Accordingly, there is a need for a novel FTP based approach that overcomes the drawbacks associated with the afore-mentioned Master/Slave serial encapsulation techniques of the prior art.